The present invention relates to an improved fluid mixing apparatus. An aspect relates to dispensing apparatus. One aspect relates to improvements in mixing and dispensing apparatus that derives the fluids passing therethrough from plural independent sources. An aspect also relates to an apparatus for mixing and dispensing chemically reacting liquids derived from plural sources such as the polyol and isocyanate which are reactable to form a thermoset polyurethane in connection with which by way of example but not limitation the invention will be described.
Reference is here made to U.S. Pat. No. 3,912,234 by John W. Peter which illustrates a system for mixing reacting liquids of the sort here contemplated. In that patent is described a mixing head. The present invention constitutes an improvement over the mixing head there described and is intended for a similar, indeed identical, application.
The present invention is more readily manufactured than its predecessor, provides an improved mode of adjustment to permit changing the volume of mixed fluids to be dispensed and other advantages and features.
More particularly this invention concerns apparatus for mixing a plurality of liquids, directing the mixture into another device (probably a mold), and then cleaning the apparatus with a plunger by forcing the remaining mixture into a chamber downstream thereof comprising: a housing having walls; a mixing chamber surrounded by the walls; an elongated plunger slidably fitted in said mixing chamber and peripherally engaging the continuous walls of the mixing chamber; a drive means for reciprocating the plunger supported on said housing and including therein a driving fluid chamber substantially coaxial with the plunger axis, a drive piston having faces on its ends reciprocably fitted within the chamber and secured to one end of said plunger, said fluid port means for communicating to the driving fluid chamber to admit and remove driving fluid to at least one face of the piston; stroke adjusting means mounted on the drive means for adjusting the piston stroke hence to adjust the stroke of said plunger; first and second ports which are preferably rectangular slots in the mixing chamber wall opening directly into the mixing chamber from respective positions opposite each other; first and second passageways for fluid through the housing walls and connected, respectively, to the first and second ports; said stroke adjusting means being adjustable to move said plunger sufficiently to block and to unblock by a preselected amount said ports; and the piston being disposed between the mixing chamber and the adjusting means the three of which are substantially coaxial with said plunger. A removable sleeve construction within the housing preferably defines the mixing chamber.